1. Field of the Invention
This invention relates to exposed surfaces with separable, discrete matter thereon and, more particularly, to a method for separating, and potentially controllably removing, the matter from those surfaces.
2. Background Art
Cargo ships, especially dry-bulk cargo and liquid-bulk cargo ships, are used to transport a wide range of products and materials on waterways worldwide. In one known dry-bulk cargo ship construction, multiple cargo holds are formed in the ship's hull to accept bulk quantities of particulate material. Each cargo hold is bounded by a ferrous wall structure and has an overhead access for loading and unloading of the materials. A typical cargo hold may have length and width dimensions on the order of 100 feet, a height on the order of 60 feet, and in excess of 220,000 square feet of exposed, interior, surface area.
A description of the transportation of powdered cement in a dry bulk cargo ship will be provided hereinbelow to demonstrate some of the problems that have plagued this industry. In a typical operation, a cargo hold will be filled with the cement at a load port. At the destination port, the cement is discharged. Loading and discharge of the cement is carried out using any of a number of different, well-known techniques and equipment. These techniques are designed to remove the majority, but not all of the bulk cargo. The balance of the residual cargo, as well as residues of previous cargo, other debris, loose rust, scale, loose paint and other potential contaminants such as stains, must also be removed prior to loading another cargo at the same or a different load port.
In the event that the hold is refilled with cement, the preparation of the hold for reloading may be minimal. However, if the next cargo is different, all interior surfaces of the hold, including the walls of the hold, may have to be thoroughly cleaned so as to not contaminate the new product with the cement residue that adheres to the walls, overhead and other structures, fittings within the hold, and hatch covers.
Heretofore, the cleaning of the walls and other surfaces within a cargo hold has been time and labor intensive and has further required relatively expensive equipment. Ladders are sometimes used to clean the lower areas of the hold, and a lift structure is often introduced to each hold to clean the upper areas. Each lift consists of a self-powered vehicle with a repositionable support for a bucket, within which a worker resides during the cleaning process. The vehicle must be strategically maneuvered into different locations to allow the worker to access the full areal expanse of the cargo hold wall.
The shipping industry has utilized the above techniques for decades and has contended with a number of problems associated therewith due to the fact that better alternatives have not been available, especially to clean inaccessible areas of the hold and hatch covers. First of all, this type of cleaning equipment is relatively expensive for a number of reasons, including the necessary delivery time and costs from anchor. The cleaning of the ship is very slow because only a few workers on the lift are able to clean the ship at one time. When working from ladders, additional labor is required to hold the base of the ladder, further depleting the normally available labor pool and slowing the overall cleaning operation. The refilling and deployment of the ships are therefore delayed, with a consequent loss of revenue.
Second, these conventional vehicles require that the workers be elevated to heights that are inherently dangerous. Personnel manning these vehicles must be trained and certified in their operation, and thus have a relatively high skill level and must exercise extreme care to avoid injury. This type of labor is generally expensive and often unavailable at cleaning locations to meet demands. The use of ladders at this height also causes workers to be precariously situated.
Third, the size and configuration of a hold may limit the number of vehicles that can function at the same time therein. The use of a single vehicle in each hold may delay the cleaning process for days, during which cleaning and docking expenses are incurred without any generation of revenue.
Fourth, if multiple vehicles are operated at the same time in a given hold, an even higher level of skill in operation may be required to coordinate the efforts of the workers in an efficient and safe manner and to place additional lifts into the hold of a rocking ship with a crane. In addition to the risk to workers, lift equipment is often damaged during these maneuvers. Safety and efficiency are further challenged by reason of the fact that these operations, to remove fine particulate cement, may cause the particles to be entrained in the air and completely fill the space in the hold, which impairs visibility and additionally exposes the workers to health risks associated with inhalation of these particles.
Fifth, these vehicles are generally powered by fuels that cause byproduct emissions that become confined in the hold. This introduces an additional health risk to the workers and limits the times when the ship can be cleaned. During periods of precipitation, the holds cannot be cleaned due to the dangerous emissions which accumulate when the holds are covered to keep them dry.
The shipping industry is highly competitive. Consequently, efficiency becomes a primary focus of those in this industry. A ship in port is doing nothing more for its owner/operator/charterer than generating expenses. Any crew that is not participating in the cleaning process is being paid for down time. Docking, fuel, and other fees accrue on a daily basis. Charter times are usually calculated in six minute intervals. Thus, it is clearly in the interest of the owner/operator to quickly, safely and efficiently clean the cargo holds and refill the same to allow transportation of materials and generation of income after the ship is certified clean and placed “on hire”. Unfortunately, an emphasis on efficiency may cause a compromise in safety in the cleaning operations. Even on an expedited schedule, however, the preparation of five to nine separate cargo holds may take as long as 3-5 days, or longer.
Many of the above problems are inherent to cargo ship holds by reason of their significant expanse. However, other exposed surfaces in those environments in which discrete, pourable matter is stored and/or conveyed present a particular problem to those that are required to treat them, either by reason of separating matter therefrom or applying a surface preparation product thereto.
There are a number of exposed surfaces, both flat and contoured, that exist in cargo holds, on hatch covers, and in other environments, that require special measures to separate adhered matter. The matter may be foreign matter that becomes adhered to a surface by reason of contact with that surface, such as in the event of a separately stored material that contacts the surface. Alternatively, the matter may have been generated from the surface itself, be it by rust, corrosion, loose paint, interaction with a component, or infliction of some damage to the surface. Regardless of the origin of the matter, it is often present in such a manner that it is either a) adhered with a significant tenacity to the surface or b) located at a contour such that is not readily accessible to be dislodged, as by a brush or scraper.
As noted above, these conditions may be present in ship cargo holds and other environments, such as silos, storage tanks, barns etc. Further, this condition is not peculiar to environments in which materials are stored. As one example, material conveyors have surfaces which support matter and otherwise come into contact with the matter that must be cleaned during use. For purposes of explanation herein, the number of the field conditions with which the present invention is adapted to address will be described with respect to the shipping industry, with it being understood that the application is not so limited.
In a ship's cargo hold, a number of surface configurations are routinely encountered. In addition, each cargo hold may have its own unique configuration which impairs access and complicates the process of separating matter from exposed surfaces thereon.
Typical to ship holds are corners at which side walls, floors, and ceiling surfaces meet. Ladders and stairs for ingress and egress are also common to this environment. A crew cleaning a ship's cargo hold can also anticipate encountering ledges, hatches with various recessed contours, etc. It is also common in the shipping industry to bound cargo holds with corrugated panels and steel beams.
Heretofore, those cleaning ship cargo holds have had essentially two options. The first option is to use currently available equipment to access these hard-to-reach areas directly by the worker on a lift or ladder. This typically involves using lifts for higher surfaces to situate the worker in close proximity to the particular condition. While some such surfaces may be reasonably accessible, most surfaces are not, due in part to their height. At some locations, the matter to be separated, by reason of this inaccessibility due to either height or some obstruction, may be accessed as by a blast of pressurized air, which causes light particles to become entrained in the surrounding area. As previously noted, this creates a health risk to the workers and also potentially obstructs vision.
Some structures also create other unique conditions that must be contended with by those cleaning surfaces in these environments. For example, at upwardly facing ledges and other transition areas, a significant accumulation of matter may occur. Breaking up a large accumulation of such matter typically is accomplished by directly accessing the accumulations, potentially at dangerously high locations. Alternatively, blasting such accumulations may aggravate the aforementioned problem of entraining the lighter particles, which creates health risks and obscures workers' vision within the hold.
Accordingly, a second option in the industry to avoid these time consuming efforts is to focus the cleaning operation on bulk recovery, without spending the time required to separate matter by accessing these surfaces. This practice may contribute to the deterioration of surfaces over time. The residue may also contaminate subsequently loaded materials. This latter option is almost inevitable in certain environments in which surface intricacies are such that it would be impractical for workers to directly access and/or break loose the matter at a number of different locations.
As eluded to above, the cleaning process is not limited to separately adhered matter, but may also involve removing stain and rust and scale that is adhered with a tenacity sufficient that it is not easily broken loose, as by a brush passing thereagainst. Consequently, there is a need to take other measures to remove this type of potential contaminant. In a large volume space, in which there may be over 220,000 square feet of surface to treat, such a cleaning operation may represent an enormous amount of down time as crews maneuver and use equipment that requires that the ship be at rest in port.
Another operation that is commonly undertaken is the application of a component preparatory to storage of a particular type of material. Ideally, an additive would be applied to each surface which the material contacts. This may be a labor intensive process, particularly in large spaces wherein workers have been required to be placed in close proximity to the surfaces to which the additive is applied. Conventional application techniques may be inadequate to apply the additive to surfaces that are intricate, in tight spaces, or not readily accessible.
The shipping industry has for the most part contended with the above problems, most notable which are significant down time, expensive cleaning processes, and potentially ineffective cleaning of ship cargo holds. The industry continues to be in need of improved methods and apparatus for cleaning foreign matter from, and treating, such surface areas.